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Scientists Discover New Form of Crystalline Order with High Potential for Thermoelectrics

Since the 1850s scientists have known that crystalline materials are organized into 14 different basic lattice structures. However, a team of researchers from Vanderbilt University and Oak Ridge National Laboratory (ORNL) now reports that it has discovered an entirely new form of crystalline order that simultaneously exhibits both crystal and polycrystalline properties, which they describe as “interlaced crystals.”

>” […] The interlaced crystal arrangement has properties that make it ideal for thermoelectric applications that turn heat into electricity, they report. The discovery of materials with improved thermoelectric efficiency could increase the efficiency of electrical power generation, improve automobile mileage and reduce the cost of air conditioning. “We discovered this new form while studying nano particles,” said Sokrates Pantelides, University Distinguished Professor of Physics and Engineering at Vanderbilt, who coordinated the study. “It most likely exists in thin films or bulk samples, but it has apparently gone unnoticed.” […]

According to the researchers, the interlaced crystal structure may be just what is needed to optimize thermoelectric applications for power generation or cooling. Thermoelectric devices need a material that is an excellent electrical conductor and a poor conductor of heat. The problem is that materials like metals that are good electrical conductors also tend to be good heat conductors and vice versa. Defects and grain boundaries that retard heat flow also reduce electrical conductivity. In addition to CuInS2, there is a large class of materials that should have similar interlaced structures. When made into thin films, they should be excellent thermoelectric materials, the researchers predict. “We haven’t tested this yet, but we are confident that these materials have high electrical conductivity and low thermal conductivity…just what you need for thermoelectrics. The field is now wide open for scientists who can fabricate thin films and make thermoelectric measurements,” said Pantelides.”<